The deposition of polycrystalline diamond films is a well established technology, but there still remain several areas which need to be addressed: growth rate, heteroepitaxy, minimizing graphitic component, and control of the surface roughness, to name a few. The surface roughness associated with the growth for polycrystalline diamond remains a problem for several areas, e.g., heat management, optical and tribiological applications. Different methods have been employed to help solve this problem with varying degrees of complexity. One of the simplest methods has taken advantage of the inability of diamond to withstand machining of ferrous materials such as Fe or Ni. Under certain conditions of heat and pressure carbon tends to diffuse into the metal which is in contact with the diamond, forming a carbide layer which is polished away. (See Want et al., SPIE Diamond Optics III 1325:160 (1990); and Yoshikawa, M., SPIE Diamond Optics III 1325:210 (1990)). However, the time needed can be on the order of hours to several weeks depending on the conditions of temperature, ambient atmosphere, and prior surface treatment. The most efficient polishing is done at high temperatures (in the 750.degree. to 950.degree. C. range), thereby precluding polishing in anything but a vacuum or non-oxygen environment.
Other methods that have been investigated are planarizing with a laser (see Yoshikawa, M., SPIE Diamond Optics III 1325:210 (1990)), etching with oxygen and argon ion beams using a planarizing layer spun onto the diamond (see Tianji et al., SPIE Diamond Optics III 1325:210 (1990)), and more recently the diffusion of carbon from the diamond into Fe or Mn during a high temperature (about 900.degree. C.) anneal followed by an acid etch to remove the carbonaceous layer (see Jin et al., Appl. Phys. Lett 60:1948 (1992)). In the latter case a mechanical polish was also necessary to completely remove the residue left after the anneal.
To minimize complexity, a polishing method using a moderately low temperature that can be carried out at atmospheric pressure, without the necessity of special gases and mechanical motion, is desirable.